Fung Kayleigh L Y, Skowron Stephen T, Allen Christopher S, Khlobystov Andrei N
School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
Electron Physical Sciences Imaging Centre, Diamond Light Source Ltd., Oxfordshire OX11 0DE, UK.
Chem Commun (Camb). 2021 Oct 12;57(81):10628-10631. doi: 10.1039/d1cc03827c.
A methodology for measuring activation parameters of a thermally driven chemical reaction by direct imaging and counting reactant molecules has been developed. The method combines the use of single walled carbon nanotubes (SWNTs) as a nano test tube, transmission electron microscopy (TEM) as an imaging tool, and a heating protocol that decouples the effect of the electron beam from the thermal activation. Polycyclic aromatic perchlorocoronene molecules are stable within SWNTs at room temperature, allowing imaging of individual molecules before and after each heating cycle between 500-600 °C. Polymerisation reaction rates can be determined at different temperatures simply by counting the number of molecules, resulting in an enthalpy of activation of 104 kJ mol and very large entropic contributions to the Gibbs free energy of activation. This experimental methodology provides a link between reactions at the single-molecule level and macroscopic chemical kinetics parameters, through filming the chemical reaction in direct space.
一种通过直接成像和计数反应物分子来测量热驱动化学反应活化参数的方法已经开发出来。该方法将单壁碳纳米管（SWNTs）用作纳米试管、透射电子显微镜（TEM）用作成像工具，以及一种将电子束的影响与热活化解耦的加热方案相结合。多环芳香全氯并四苯分子在室温下在单壁碳纳米管内是稳定的，这使得在500 - 600°C之间的每个加热循环前后都能对单个分子进行成像。聚合反应速率可以通过简单地计数分子数量在不同温度下确定，从而得到104 kJ/mol的活化焓，并且对活化吉布斯自由能有非常大的熵贡献。这种实验方法通过在直接空间中拍摄化学反应，在单分子水平的反应和宏观化学动力学参数之间建立了联系。
